The nine characters who appear as series regulars in the first season all work in the fictional Seattle Grace Hospital. Five of the characters are interns: Meredith Grey portrayed by Ellen Pompeo, who is in a romantic relationship with her attending Derek Shepherd, and is the daughter of the renowned surgeon Ellis Grey, who now suffers from Alzheimer's; Cristina Yang portrayed by Sandra Oh, an extremely competitive intern who befriends Meredith and begins a sexual relationship with Preston Burke; Izzie Stevens portrayed by Katherine Heigl, an ex model who struggles to be recognized as a doctor; Alex Karev portrayed by Justin Chambers, an arrogant intern who initially irritates his colleagues, and George O'Malley portrayed by T.R. Knight, a unsecure intern with a lack of confidence, who develops a crush on Meredith. The interns are mentored by their resident Miranda Bailey portrayed by Chandra Wilson, a disciplined woman who is nicknamed "The Nazi". The surgical program is lead by the Chief of Surgery Dr. Richard Weber portrayed by James Pickens Jr.. In his employ are Preston Burke and Derek Shepherd portrayed by Isaiah Washington and Patrick Dempsey...